1. Field of the Invention
The present invention relates to a process for producing a polynitrile compound comprising reacting a carbon ring or heterocyclic compound having a plurality of organic substituents with ammonia and a gas containing oxygen. More particularly, the present invention relates to a process for producing a carbon ring or heterocyclic dinitrile compound from a carbon ring or heterocyclic compound having two organic substituents.
2. Description of the Related Arts
Polynitrile compounds and, in particular, carbon ring dinitrile compounds are useful as raw materials for synthetic resins and agricultural chemicals and as intermediate compounds for amines and isocyanates. Heterocyclic dinitrile compounds are useful as intermediate compounds for drugs and additives for feed and food.
The process of reacting an organic compound such as a carbon ring or heterocyclic compound having organic substituents with ammonia and a gas containing oxygen is called ammoxidation and, in general, nitrile compounds are produced in accordance with a gas phase catalytic reaction.
It is known that catalysts containing vanadium, molybdenum or iron are used for the ammoxidation. For example, in Japanese Patent Application Laid-Open No. Heisei 11(1999)-209332, a process for ammoxidizing carbon ring and heterocyclic compounds having alkyl groups as substituents in the presence of a catalyst containing oxides of V, Cr, B and Mo is described. In Japanese Patent Application Laid-Open No. Heisei 9(1997)-71561, a process for producing dicyanobenzene by the ammoxidation of xylene in the presence of a catalyst containing oxides of Fe, Sb and V is described.
When a nitrile compound is produced by the ammoxidation, in general, the temperature of the reaction, the amount of ammonia, the amount of oxygen and the time of contact are suitably selected so that the maximum yield of the nitrile compound is obtained. Actually, relatively severe conditions are selected so that the conversion of the carbon ring or heterocyclic compound of the raw material increases. However, the burning reaction takes place as the side reaction under such severe conditions and causes a loss of the raw material. Therefore, a process which can prevent the burning reaction and decrease the loss of the raw material has been desired.
It is possible that the conversion of the raw material is suppressed at a small value and the unreacted raw material is recycled to suppress the side reaction. However, this process has a drawback in that the one-pass yield of the nitrile compound decreases and productivity decreases.